Self-stripping mold and method of making



ay zn, 1924; r' L494Q723 A. Y. TUCKER ET AL SELF STRIPPING` MOLD ANDMETHOD OF MAKING Filed March 24v, 1922 3 Sheets-Sheet l gwvantozo ALBERT(.TucKER IsAAc AwmRous V Y 1 D.

may zu, 1924:,

A. Y. TUCKER ET AL.

SELF STRIPPING MOLD AND METHOD OF MAKING 3 sheets-sheet 2 Filed March24, 1922 @mmm/tom ALBERT YTucKER ISAAC AWATRouS May 20 1924s' A. Y.TUCKER ET Al. sDDF STRIPPING MoDD AMD METHOD oF MAKING Filed vMarch 24,

1922 5 Sheets-Sheet 3 wuemozo ALBERT Y. TUCKER ISAAC AWAY nous PatentedMay 20, 1924.

UNITEDA STATES PATENT oFFicE.

ALBERT Y. TUCKER, F MOUNT VERNON, NEW YORK, AND ISAAC A. `WATROUS, 0F

STRATFOBD, CONNECTICUT, ASSIGNOBS T0 REVERE RUBBER COMPANY, A COB-PonATIoN or RaoDE rsLAND.

SELF-sunnite now AND METHOD' or mme.

Application med umn a4, 1922. serial No. 546,222.

and ISAAC A. VATnoUs, .both citizens of the United States, and residingat Mount Vernon, in the county'of Westchester and State 1 of New York,and Stratford, in the county of Fairfield and State of Connecticut,respectively, have invented a certain new and useful Self-Stripping Moldand Method of Making, of which the following is a full, clear, andexactfdescription. u This invention relates to a self-stripping Amoldand method of making the same, more particularly-to a moldfor lmakingarticles of vulcanizable material, such as heels.I

The ordinary type otl heel mold comprises a lower section having theusual washer retaining-pins projectin upwardly therefrom, an uppersection, an an intermediate section in which are formed the cavities forthe heel. The heel blanks placed in the cavities for molding are formedwith a certain amount of excess material in order to insure completefilling of 'the cavity, andv in the F -molding operation this excessmaterial flows over the edge of the cavity. forming a sheet of flash oroverflow which unites all the heels. Hence, when the molding operationis finished it is necessary to first cut this sheet between the heels inorder that the heels may be' separated before removing from thecavities, and after removal the individual flash portions must be cutawa from each heel. In the molding of smal rubber articles an essentialfeature to economical production is speed and minimum handling in makingthem. Hencepheels made in the above described manner consume aconsiderable time in the manufacture. 1n addition, as the mold cavitiesin the in termediate section are usually formed in a solid plate, theentire section must be replaced When changing for different styles.sizes of heels, or when worn out.

An"obj.ect of our invention is to lessen the time, labor and expenserequired in making molded vulcanized articles.

Another object is to provide a self-stripping mold.

Still another object is to provide a mold in which the parts subject towear may be readily replaced.

A further object is to rovide a gang heel mold in which the me? dcavities may be changed asdesired for different styles and sizes ofheels.

A still further Objectis to provide a method of making the mold.

For a detailed disclosure of the invention reference .is had to theaccompanying specication and drawings, in which latter:

Fig. 1 is a plan view of a mold embodying our invention, with the topmold section removed; v l

Fig. 2 is a section corresponding to the line 2-2 of Fig. 1 with the topsection in place, and showing the mold at vthe completion of the pouringoperation;

Fig. 3 is a plan view of a mold cavity liner and a rigid backintherefor;

Fig. 4 is a side elevation of the same;

Fig. 5 is a plan view ofthe liner;

Fig. 6 is a plan view of a liner positioning sheet` and materialretaining wall used in making the mold; f

Fig. 7 is a plan view of a rigid liner backing slightly modified fromthat shown in 1 3; Fig. 8 is a plan view of a modified form of liner; l

Fig. 9 is a section corresponding to the line 9-9 o`f Fig.` 10, showinga modified form of mold;

Fig. 10 is a view on Fig. 9 witlrthe topl moldsection removed;

ig. 11 is a plan ofthe rigid backing emphyed inthe form shown in Figs. 9and l0; ig. 12 is al section onfthe line `12---152 of Fig. 11; and

Fig. 13 is a plan of thevliner employed with this form of backing.vReferring to Figs.` lfto 5, the numeral l designates a bottom moldsection of usual form havingseries ofrheel kWasher positioning pins 2disposed thereon, the section also the line 10-10 of being providedwithldowelpins 3. An uper mold section 4,' also of the usual form,

1s provided,which-.section is formed with a purpose to be later descried. These liners may be made by bending strips of sheet metal of theproperwidth into heel shape and joining their ends by welding orbrazing, or they may be'made by diein them out from sheet metal, thelatter met 'od-'being preferred. ln either case the liners are given aheat treatment, and the edges ground to insure their being in'parallelism and the proper distance apart. Une of the liners 6 isdisposed around each series of washer positioning ins 2, and in order toquickly and accurate y position them heels may be placed on the pins 2and the liners slid over the heels.' A thin imperforate sheet 8 (Fig. 6)of any suitable material, such as cardboard, is then placed over theliners, the top mold section applied, and the mold placed in a press.Under the heavy pressure in the press the liners cut a series of heelshaped openings 9 in the sheet, as shown in Fig. 6, and the dowel pins 3form a series of openings 10. rlhis operation is -then repeated toprovide a second sheet 8 with the openings 9, and to this second sheetnarrow strips 11 of cardboard ma be secured between rows of openings, assiown in Fig. 6, which strips arel adapted to form flash cavities in amanner to be'later described. The second sheet is also provided with apour hole 11.

The irst rforated sheet 8 is then disposed on t e lower mold section,beinev properly positioned thereon lby the doweil pins 3, registeringwith the openings 10 1n the sheet. A liner 6 is then placed in each ofthe openings 9, and around each liner is disposed a rigid` andrelatively in- `fusible backing 12. These backings 12 are ofsubstantially heel shape and provided with an interior opening largeenough to readily slip over the liner 6. 'lhe backings may be made ofany suitable material, and we have found that satisfactory results areobtained by casting them of malleable iron. Each backing is providedwith an overhanging flange 13 extending around the same, and on itsinner wall is provided with a series of regularly spaced recesses 14,leaving between the recesses projections 15 which are adapted tocooperate with the liner 6 in the molding operation vto back up the sameand prevent its collapse. These projections 15 need not, however,accurately fit or be in contact with the liners 6 for a reason to belater explained. 'lihe backing is also provided on one side withrecesses 16 extending outwardly through the dange 13, and on the otherside with a series of recessesvl?. After disposing a backing 12 aroundeach liner a frame 18 is dis osed on the sheet 8 around the whole, therame having formed on its inner wall grooves 18 fora purpose to be laterexplained,

and also `having openings 19 for the reception of the dpwel pins 3.Brace rods or liners and backings.

wires 20 are "secured in opposite sides of the `tranne and extend acrossthe latter at right angles to each other between adjacent Olne side ofthe frame is also provided with vent openings 21. Thefsecond linerpositioning sheet 8 is then neueres disposed over the frame with itsopenings 10 in registry with the dowel pins 3, its strips 11 turnedinwardly, and the openings 9 disposed around the upper edges of theliners 6, as shown in Fig. 2. lt will be noted that the backings -12 aremade of a height or thickness less than the height of the liners 6 bydouble the thickness of a, sheet 8, so that the spaced sheets 8 not onlyaccurately, position and space each liner in the mold, but they alsoaccurately position the backing 12 so that the liner will project aboveand below it to the required distance. The top vmold section is thenclamped in position, this section being temporarily provided with a pourhole 22, in registry with the opening 11 in the sheet 8. Any suitablepouring funnel may be secured in the opening 22,kthe mold turned onedge, and

`fusible material 23, such vas any suitable low melting point alloy, ispoured into the opening 22 completely filling'all cavities outside ofthe liners 6 between the two sheets 8, the openings 21 acting as ventsduring this operation. The perforated sheets 8 not only have a linerspacing and positioning function, as before described, but also act asretaining walls for the fusible material during the pouring of the ma-yterial in the mold making operation.- rl`his backing material completelylls in the recess'es 18 in theframe, the spaces in the recesses 14, 16and 17, and also fillslin the space or spaces where any of thepr0jections 15 are not in contact with the liners 6. The fusiblematerial 23 therefore not only acts as a backing for the liner, but italso securely anchors the latter to the backing 12, and both `ot them tothe frame 18. The brazed spots 7 on 'the liner 6 aid in securing thelatter in position. The cardboard sheets 8 are then removed, the pourhole 22 pluggedup, and the mold is ready yfor use, the strips 11 on theupper one of the sheets 8 having formed the flash cavities 23 in thefusible backing 23.

The -backings 12 may be cast separately, as shown in Figs. 1 to 4, butin orderwto save material, time and labor it is preferred to cast anumber of them together, andin Fig.A 7- one embodiment of this idea isillustrated. ln this form the body portion 2d around each linerreceiving openin is iden- `tical with the backing 12, but t e flangeemployed. These liners are identical with the form shown in Fig 5, butare provided with attaching ears 27 to more securely anchor them in 'thefusible backing. However, when using the ordinary low melting pointalloys the backing tends to soften under the heat of the heel moldingoperation, and the great pressure exerted vrenders the liner` 6 liableto buckle, hence we preferto incorporate some'form of rigid andrelatively infusible backing to assist the if the thickness of the linerbe reduced to fusible material in preventing buckling or collapse of theliners.

In Figs. 9 to 13 another form of the invention is shown. in which thelower and', upper mold sections may be of any suitable type, as in Figs.1 and2, and the intermediate section is formed by a frame 28 to one sideof which a plate 29 is secured. as by the rivets 30, or in any othersuitable manner. A series vof heel shaped openings 31 are cut in thisplate, which openings are of a size somewhat larger than the liner withwhich they are to be used. A rigid and relatively infusible linerbacking 32 is provided for each opening, which has a i'educed lowerportion'33 adapted to fit within the opening 31, and an overhangingflange portion 34, adapted to rest on the late 29, to which latter itmay be secured 35in any suitable manner, as by the rivets 35.

This backing'may be formed in a manner similar to that employedYformaking the backing 12. Around the inner wall of each lbacking' aseries of arc shaped saw kerfs 36 40 vare made, and recesses 37 in theinner wall lead from these kerfs to the upper side of the backing;` Theliner 38 is similar to vthe liners shown in Figs. 5 and 8, but is notprovided with any securing means, and itis made of a size to exactly fitWithin the opening in the` backing 32.- After disposing the liners intheir backings they are secured in position by -flowing a small -amountof brazing metal into the openings 37 andy kerfs 36.

and the mold put in the vulcanizing press.

Under the influence of the heat and pressure the heel blanks flow,filling the cavities in the liners and finally flowing over the edge ofthe liners. However, owing to the thin v and sharply defined projectingedge of the ,liner the vflash at the point of connection to the heel isreduced to an extremely thin ragged film. After the vulcanizingoperation is completed the mold is taken out of the press, the top andbottom sections re- 'molded articles.

moved, and the heels knocked out of the liners. During this lastoperation the sharp projecting edge of the linersevers or tears off theflash at the point immediately adjacent the heel where the flash hasbeen thinned down as above mentioned. It has been found that aprojection of the liner of 312 of an inch beyond the backing issufficient for the purpose, although this distance may be varied withinlimits. However, it is obvious that if the `projection be made too greatin length the liner will tend to buckle, owing to lack of any backing towithstand the pressure during the vulcanizing operation. It has alsobeen found that too great an extent itv will tend to buckle under thepressure, while if the thickness is made too great it will fail to causethe thin film of flash around the heel. It has been found that by makingthe liner from material of a thickness between 20 and 30 thousandths ofan inch these objections are obviated.

It will be seen that in each form of our invention a thin hard liner isprovided for the mold cavity, and that this liner is secured in theframe of the mold by a connection of fusible material. Therefore, ineach o f the forms the liner when worn may be readily replaced by merelyheating the moldsection sufficiently to melt the' fusible connection andreplacing Athe liner by a new one. It will also 'be seen that in eachform of the invention the thin edge of the liner projecting beyond thebacking forms a mold which is in` effect self stripping. ln the formsshown in Figs. 1 to 8 it will also be Aseen that different sizes andshapes of artistituting others suitable for the article to be molded.

By our vinvention a mold section is provided which fully accomplishesthe purpose set forth in the objects, and considerably reduces the timerequired in the making of 'While in the specific embodiment shown. theinvention has been described as applied to the making of heel molds, itis evident that it is not limited in its application, as it may be usedfor making numerous other molded articlesfrom vulcanizablematerials,fand that many modifications may be made in the details withinthe scope of the appended claims.

Having thus described our invention, what we claim and desire to protectby Letters Patent is:

1. A self stripping mold section comprising a relatively thin liner, anda ybacking therefor of less height than that of the liner adjacentthelatter.

.2. A self stripping mold section comprising a lrelatively thin liner,and a' readily removable backin therefor of less height than that of thet(liner adjacent the latter.

3. A self stripping mold section comprising a relatively thin liner, anda readilyv fusible backing therefor of less height than that ofthe lineradjacent the latter.

4. A selfstripping mold section comprising a relatively thin liner, anda backing therefor terminating slight-ly short ofthe bottom andtop edgesof the liner.

5. A self stripping mold section comprisingv a relatively thin liner,and a readily removable backing therefor terminating slightly short ofthe bottom and'top edges Aof the liner.

6. A self stripping mold section comprising a relatively thin liner, anda readily fusible backing therefor terminating slightly short of thebottom and top edges of the liner.

7. A self stripping mold section comprising a relatively thin hard metalliner, a relatively rigid and infusible backing there.- for, and fusiblemeans for securing t e liner to the backing. 4

8. A self'stripping mold section comprising a relatively thin liner, arelatively -ini fusible backing cooperating with the liner Lil) atspaced points, and a fusible backing also cooperating with the liner.

9. A self stripping mold sect-ion comprising a relatively thin liner, a'rigid and relatively infusible backing cooperating there- 4withat-spaced points, and a fusible backing cooperatingl with the liner atpoints intermediate said first points.

10. A self stripping mold section com rising a relativelyY thin liner, afusible bac 4in'g surrounding the same, and a relatively infusiblebacking for the liner imbedded in said first backing. y

11. .A self stripping mold section com rising a relatively thin liner, afusible bac ing surrounding the same, and a relatively infusible backingfor the liner imbedded in said first backing, said backings bein of lessthickness than the height of the hner.

12. A self strippingmolu section com rising a relativelyv thin liner, afusible bac ing surrounding the same. and a relatively infusible backingfor the linerimbedded in said first backing, said backings terminatingslightly short of the bottom vand top edges of the liner.

13. Aself stripping mold section comprising a relatively thin liner, arigid b acking therefor, said backing bein recessed on its side adjacentthe liner an at a plurality of other pointsyand a fusible backing flowedinto said recesses and filling all space between said lner and the rigidbacking.

14h-A self stripping mold section comprising a thin hard metallic moldcavity liner, a relatively rigid and infusible recessed metal backingsurrounding the liner and cooperating therewith at spaced points, and afusible backing filling the recesses and space between the liner andbacking, said backings terminating slightly short of the top and bottomedges of the liner, whereby in molding the flash may be reduced to athin film adjacent the mold cavity.

15. A self stripping mold section comprlsing al frame, a relatively-thin mold cavity liner disposed therewitliimand fusib'le` means forsecuring the liner in position.

prising" a frame, a relatively thin mold cavity liner disposed therein,and a backing of fusible material interposed between the liner and frame'and securing the liner in position.

17. A self stripping mold section comprising a frame,- a relatively thinmold cavity liner disposed therein, abacking of relatively infusiblerigid material coo erating with the liner, and a backing of usiblematerial also cooperating with the \liner and securing theliner and saidfirst backing in position.-

18. A self strippingimold section com- 16. A self stripping mold sectioncom-l prising' a frame, a relatively thin mold cavity liner dlsposedtherein, a relativelyinfusible backing surrounding the liner, saidAbacking being recessed on its side adjoining the hner, and a fusiblebacking within the frame and lling the open spaces between the firstbacking and liner.

19. A self stripping gang mold section comprising a frame, a series ofmold cavity liners disposedgtherein, and a backing for said linersrigidly connected to the frame,

leach liner extending above and'below the 22. A self stripping gangmold` section comprising a frame, avseries of mold cavity linersdisposed therein, a'rlgid and relatively infusible backing foreachliner, a fusible backing connectingeach liner to its 'first meanssecured to the frame and extending through said fusible backingbetweenadja-l cent infusible backings.

23. A self stripping gang mold section named backing andfto the frame,and bracing comprising a relatively infusible and rigid i. backing, saidbacking having a plurality of mold cavities therein, a thin hard linerdismamas posed in each cavity, and a fusible lation with a mold cavityliner in each pair connecting each liner to the infusible one.

24. A self stripping gang mold section comprising a rel-ativel infusibleand rigid backing, said backing having a plurality of mold cavitiestherein, a thin hard liner disposed in each cavity, said liners havingtheir bottom and top edges extending in the same horizontal planes andslightly beyond the backing, and a fusible backing connecting saidliners and firstl backing and of substantially the same thickness as thelatter.

25. A self stripping gang mold section comprising a frame, a series ofrelatively infusible backing members disposed therein, each of saidmembers having a series of mold cavities therein, a thin hard linerdisposed in each cavity, and a backing of fusible material connectingthe liners and backing members to each other and to the frame. 26. Agang heel mold includin upper,

lower and intermediate sections, said inter-l mediate section comprisinga frame adapted to be clamped between the other two sections, a seriesof thin hard mold cavity liners within the frame and having upper andlower edges adapted to engage the corresponding mold sections, arelatively infusible backing for each liner, and a fusible backing foreach liner connecting the liners, infusible backing and frame, saidbackings being slightly spaced from the top and bottom mold sectionswhereby in molding the ash may be reduced to a thin film adjacent themold cavities.

27. The method of making mold sections which comprises forming a moldcavity liner of thin 'hard metal, dis 'sing' spacing and retaining wallsaround t e liner adjacent lts ends, flowing a backing of fusiblematerial around the liner within said walls, and removing the walls. y

28. The method of making mold sections which comprises forming a moldcavity liner of thin hard metal, disposing spacing and retaining wallsaround the liner adjacent its ends, interposing between said walls andaround the liner a backing of relatively infusible material, owing abacking of fusible material into the space within the walls around theliner, and removing the Walla A 29. The method of making intermediatemold sections for three part gang molds which consists in providing twoliner positioning walls yhaving corresponding liner opening, disposingmid walls in spaced reof corresponding openings, flowing a backing offusible material around the liners between said walls, and removing thelatter.

30. The method of making mold sections which comprises formin a moldcavity liner of thin hard metal, disposing a backin of rigid andrelatively infusible materia around the liner, and securing the liner tosaid backing by a fusible material.

31. The method of making intermediate i mold sections which comprisesdisposing a thin hard mold cavity liner and, a frame be tween up r andlower mold sections, with spacing e ements surrounding the liner andinterposed between said frame and the upper and lower mold sections, andlling the space between said elements, the liner and the frame with afusible backing.

32. The method of making intermediate mold sections for three part gangmolds which consists in disposing on one outer section a perforatedliner positioning wall, disposing a thin mold cavity liner in eachvperforation and a frame around the liners,

superposing a second perforated liner positioning wall on the frame withthe liners projecting into its perforations, clamping the other outermold section over said last named wall, and flowing a backing of fusiblematerial around the liners between said walls.

33. The method of making intermediate mold sections for three part gangmolds which consists in disposing on one outer section a perforatedliner positioning wall, disposing a thin mold cavity/'liner in eachperforation, placing a relatively infusible backing on the wall aroundeach liner and a. frame around the whole, superposing a secondperforated liner positionin wall on said backings and frame with theliners projecting into the perforations, clamping the other outer moldsection over said last named wall, and dowing a'lbacking'of fusiblematerial into the space around.' said liners e Isaac-1a. wArnoUs.

